The present invention relates to an optical or optoelectronic module, of the type used, for example, as a source of signals which are transmitted over optical fibers. By means of modules of this type, emitted light from a semiconductor laser is fed into optical fibers, which is required for applications in the areas of telecommunications, for example, pumping lasers, printing and photographic technology, materials processing, medical technology, illumination and display technology, metrology or analytics.
Optical modules of this type are disclosed, for example, in publications U.S. Pat. Nos. 4,818,053 and 4,997,279. Each of them shows an optical bench on which a semiconductor laser, an optical fiber and a focusing lens in a bracket is positioned to transmit the emitted radiation from the semiconductor laser into the optical fiber, where the fiber is mounted in a fiber sleeve. Both the lens and the optical fiber are oriented longitudinally along the optical axis of the beam emitted by the laser.
The adjustment of the two components is carried out in such a way that first of all the focusing lens is adjusted in three stationary degrees of freedom of translation along the optical axis of the beam emitted by the laser. After the lens has been fixed in position, the optical fiber in turn is adjusted in three degrees of freedom of rotation along the optical axis and fixed in position. The disadvantage here is that the adjustment of the two components is performed sequentially in two separate steps. This requires a high degree of sophistication in the equipment as well as the expenditure of a great deal of time.
The object of the present invention is to make available an optical or optoelectronic module which can be assembled and adjusted simply and which ensures a precise beam pattern during its entire life and even under adverse conditions.
The module under the invention has a first assembly holder as well as a first element holder, where at least one focusing lens and an optical fiber are located on the first element holder in appropriately shaped seats. This array can be set up without any adjustment. The first element holder for its part is located at the first assembly holder, which in turn again is located on an optical bench. The path of the common optical axis of the optical or optoelectronic assembly thus formed is determined by the orientation of the optical axes of the focusing lens, optical fiber and any additional optical and/or optoelectronic components to each other and is thus dependent on the manufacturing tolerances of the element holder. By adjusting the optical assembly in up to three degrees of freedom of translation and up to three degrees of freedom of rotation within a single adjustment step, the optical axes of the assembly and of the beam emitted by the laser diode can be aligned to each other, and the optimal distance of the laser diode to the optical assembly can be set. As a result of this inventive configuration of the optical or optoelectronic array it is possible to locate all the optical and/or optoelectronic components positioned on the element holder jointly in the beam path of the light emitted by the laser diode and thus to obtain/achieve a simple and correct adjustment of the optical or optoelectronic module.
The first element holder and the first assembly holder are advantageously formed in such a way that the first element holder is movable in all degrees of freedom with respect to the optical bench.
One configuration of the assembly holder, for example, is a U-section open at the top between the flanges of which the element holder is located. The distance between the two flanges is dimensioned such that only a small gap remains on both sides of the element holder between the element holder and the flanges. During the process of adjustment and locking in position, the element holder is held, for example, by a gripping device which is mounted on a positioning system. By means of this positioning system, which can moved advantageously in 6 axes, the element holder and thus the optical module are adjusted for position. Because of its particular configuration, the first assembly holder is moved as well on the assembly surface of the optical bench during the positioning procedure for the first element holder, so that a subsequent adjustment of the assembly holder is not necessary.
After adjustment has been completed, the first element holder can be locked in position in the assembly holder with adhesive, and the assembly holder can be held in position on the optical bench. In this process, the first element holder is held in position only laterally against the flanges of the assembly holder, and the assembly holder is only held in place with its underside on the assembly surface of the optical bench. The open space between the first element holder and the upper side of the base plate of the first assembly holder is advantageously not filled with adhesive.
Because of the special configuration of the assembly holder and of the element holder, the gaps between the first element holder and the first assembly holder are extremely narrow, and so only a small gap has to be bridged with adhesive. The result is that material shrinkage of the adhesive during curing is negligibly small. As a consequence, the adjustment of the element holder in the assembly holder remains unchanged even after the adhesive has cured.
Some examples of optoelectronic modules under the invention are given in the ensuing descriptions.